Torque release and shutoff device for rotary tools



June 2, 1970 J. M. CLAPP 3,515,251

TORQUE RELEASE AND SHUTOFF DEVICE FOR ROTARY TOOLS Original Filed Aug. 29, 1967 INVENTOR JOHN M. CLAPP AGENT United States Patent Office.

3,515,251 Patented June 2, 1970 3,515,251 TORQUE RELEASE AND SHUTOFF DEVICE FOR ROTARY TOOLS John M. Clapp, Athens, Pa., assignor to Ingersoll-Rand JCompany, New York, N.Y., .a corporation of New ersey Continuation of application Ser. No. 664,158, Aug. 29, 1967. This application Apr. 14, 1969, Ser. No. 824,720 Int. Cl. F16d 7/00 U.S. Cl. 192-150 20 Claims ABSTRACT OF THE DISCLOSURE In a power tool a torque-responsive clutch having camming means to turn ofl? the motor; applicable to reversible type tools as well as uni-directional types.

This is a continuation of applicants co-pending patent application, Ser. No. 664,158, filed Aug. 29, 1967, entitled Torque Release and Shut Off Device for Rotary Tools, now abandoned.

This invention pertains to clutches and in particular to torque-responsive clutches which shut-off the driving motor upon reaching a preset torque value.

Such clutches known in the prior art are often of the stall type in which, upon reaching the preset torque value, the motor is caused to stall as the driven chuck is held in the workpiece, i.e., the member being driven. Upon withdrawal of the power tool from the workpiece the motor is released and the chuck is free to spin. In devices of this type there is a difliculty in that upon removing the chuck, and the driving tool held therein, from the workpiece, the motor is then freed, and the tool will spin immediately, causing deformation of the drive slot, driving head, or socket of the workpiece, causing damage to the driving tool itself, or putting the operator in danger of injury from the spinning, unloaded tool.

Other devices in this art having a torque-responsive clutch use a locking means, such as a sear or a latching device which is responsive to axial pressure along the chuck to enable the motor but has a linkage which, upon realization of the desired torque, releases the locking means. The linkages involved in these arrangements are rather complex; they function only through the enabling of a plurality of serially-arranged, inter-dependent devices; they require that one clutch member move axially relative to another clutch member, upon reaching the predetermined resistance to the rotation of the chuck, so as to move a drive rod, to release a sear, or locking member, to shut off power. Many of these prior art mechanisms are usable on but uni-directionally-rotated tools, or are usable on reversible tools but have torqueincreasing utility in one direction and only total torque in the reverse direction.

It is an object of the present invention therefore to provide an improved torque-responsive clutch for use in mechanically powered tools which, by way of a novelly simplified arrangement, shuts off the motor upon reaching a preset torque value. Another object of this invention is to provide a torque responsive clutch which maintains torque control during separation of the clutch engaging members while presenting a fully halted motor and chuck. Another object of this invention is to provide a torqueresponsive clutch which provides for a full run of torqning, forwardly or in reverse, and has means for disabling the motor and disengaging the clutch drive in the same last revolution of the motor drive shaft.

A feature of this invention comprises the use of a camming device between the chuck and the motor actuator rod. The camming device makes use of the last quadrant of rotation of the motor, beyond torquing-limit, to disable the motor. Further objects and features of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying figures in which:

FIG. 1 is a side view of a power tool of a type in which the novel clutch is used;

FIG. 2 is a partial cross-sectional view of a power tool such as that of FIG. 1, taken along the axis thereof, which incorporates a preferred embodiment of the torque responsive clutch according to the invention;

FIG. 3 is an axial, cross-sectional view of the valving arrangement of the power tool of FIG. 2;

FIG. 4 is a diametral cross-section of a portion of the novel camming arrangement taken along line 4-4 of FIG. 2;

FIG. 5 is a further diametral cross-sectional view of the camming plunger taken along line 5--5 of FIG. 2;

FIG. 6 is a partial axial and cross-sectional view of an alternate embodiment of the novel torque responsive clutch; and

FIG. 7 is a diametral cross-section of the camming plunger taken along the line 7-7 of FIG. 6.

Shown in FIGS. 1 and 2 is a power tool 10, which may be a pneumatically-powered screwdriver, which incorporates the novel torque-responsive clutch according to the invention. The tool 10 has a housing assembly 12 enclosing a motor means 80, shown symbolically, which may comprise an air motor. However, the objects of my invention could be equally satisfied in a power tool having electric, hydraulic, or other motor means. The motor means 80, driving through a gear train 14, powers a take-01f shaft 16 coupled thereto which drives a torqueresponsive clutch assembly 18. The power tool has a chuck 20 disposed at one end thereof for receiving a bit, or the like, for addressing a workpiece. The housing assembly 12, as is shown in FIG. 3, has an input port 22 for pressurized fluid for driving the motor means 80. Disposed between the input port 22 and the motor means is turn-on, turn-01f device 24 which is here shown to be a valve which admits fluid or prohibits the introduction of fluid to the motor means 80. Biasing means 26 shown as a compression spring urges the vlave device 24 to a closed position. An actuator rod 28 disposed in an axial bore 30 in the center of the power take-01f shaft 16 is used to unseat the valve device 24 so as to admit pressurized fluid therethrough and to the motor means 80.

The functioning and interaction of the motor means 80, the valve device 24, and the actuator rod 28 are as known to those skilled in the art from the teachings of prior patents. U.S. Pat. No. 3,082,742, issued Mar. 26, 1963, for a torque tool control to J. B. Vilmerding et al., for instance, sets forth a vane type air motor, a valve device, and an actuator rod for displacement of the latter in accordance with the purposes here similarly pursued. These elements, then should require no further explanation in this disclosure.

The torque-responsive clutch 18 includes a loading spring 32 which is under compression and bears against a thrust plate 34. The thrust plate 34 is thereby constrained against a plurality of balls 36 held by a caging plate 38 integral with shaft 16. The opposite surfaces of the balls 36 nest in recesses 40 formed, equally-spaced and radially, in a facing surface 42 of a clutch jaw 44. The chuck 20 has formed on the inner end thereof a clutch driver 46. The clutch driver 46 is a flat plate having raised portion of metal disposed across the diameter of a face thereof; it receives maXillas or jaw members 48, formed of, and extending from the interfacing surface of the clutch jaw 44, across either sides of said raised portion.

The axial bore 30 formed in the center of power takeoff shaft 16 has hexagonal and circular major portions 50 and 52, respectively. A pair of serially disposed plungers 54 and 56 are slidably mounted within the major axial bore portions 50 and 52 of the shaft 16. Plunger 54 is circular in its external configuration; plunger 56 is hexagonal. Plunger 54 has a limit pin 58 extending therefrom, the pin being disposed for a limited axial movement in a relieved area 60 provided therefor in power take-off shaft 16, and provisioned to effect a rotation of plunger 54 with shaft 16. The clutch driver 46 has a stub shaft 62 extending rearwardly therefrom which is received by a circular bore 64 formed in the center of plunger 56. Plunger 56 also has a V-shaped slot 66 formed in a side thereof through which there projects a pin 68 fixed in, and extending perpendicularly from, stub shaft 62 of the clutch driver 46. The actuator rod 28 bears against the motor-side face of plunger 54. A spring 70 urges plunger 56 toward the motor end of the tool, tending to open the valve device 24.

In operation, the motor means 80 drives the gear train 14 and imparts power to the take-off shaft 16 so as to rotate the chuck 20 through torque-responsive clutch assembly 18. The chuck 20 receives a bit which is addressed to the workpiece while axial pressure is brought to bear on the power tool This causes the chuck to sheathe or retract in the direction of the gear train 14.

Clutch driver 46 slides rearward into further engagement with clutch jaw 44. However, as clutch driver 46 slides rearward, it moves spring 70 and pin 68 simultaneously. The bias of spring 70 and translation of pin 68 displaces the plungers 54 and 56 within the major axial bore portions 50 and 52 of the power take-off shaft 16. Displacement of plunger 54 translates the actuator rod 28 so as to unseat the valve device 24 and admit pressurized fluid to the motor means 80 to enable the latter. Accordingly, the chuck-mounted bit torques the workpiece. Upon reaching a desired torque value, the torque-responsive clutch assembly 18- causes the balls 36 to rise out of the recesses 40 provided in surface 42 by way of compensating for the resistance of clutch driver 46 and chuck 20 to further rotation. This ball-drive, spring-loaded, torque-responsive clutch assembly 18 is a teaching of the same, earlier-referenced, US. Pat. No. 3,082,742. The embodiment here depicted functions in similar fashion as the manner described in the referenced patent and, accordingly, requires no detailed recitation here. It should be sufficient to state that power take-off shaft 16 imparts rotary motion to caging plate 38, and the rotation of the latter causes the balls 36 to carry clutch jaw 44 in rotation therewith. The engagement of the clutch driver 46 with the rotating clutch jaw 44 drives the chuck 20. This chain of rotation is maintained until the resistance of the workpiece which is being addressed is greater than the ability of the bias of loading spring 32 to retain the balls 36 in their recesses 40. At this point, the caging plate 38 continues to turn and the balls 36 find the loading spring 32 less resistive than the fully torqued workpiece. Accordingly, the loading spring 32 yields; it compresses sufiiciently under the pressure of balls 36 rising out of the recesses 40 and bearing against the thrust plate 34. The caging plate 38 carries the balls 36 through a quadrant of a turn where they re-nest in the next, adjacent recesses 40. Simultaneously, my novel clutch camming arrangement halts the motor, as explained in the following passages.

The chuck 20 remains stationary as the motor means 80 gives the last turn to the power take-off shaft 16 and carries the caging plate 38 and balls 36 to the adjacent indexed position. The plunger 56 being nested in hexagonal portion 50 of the major axial bore of shaft 16 must necessarily execute the same last turn. Yet, pin 68, being integral with stub shaft 62 of clutch driver 46 and chuck 20, remains stationary. Accordingly, a leg of V-slot 66 provided in plunger 56 passes over the pin 68 as plunger 56 executes that last indexed turn. In passing a leg of slot 66 over the pin 68, and in turning, plunger 56 is caused to cam forward, away from the motor-side of the tool, against the bias of the spring 70 disposed against its forward face, fully into bore portion 52. Displacement of plunger 56 provides a space therebehind into which plunger 54 moves under the urging of biasing means 26 disposed against the valve.

As explained in the foregoing, the V-slot 66 provided therein cams plunger 56 forward so as to allow plunger 54 to move axially, forwardly. Actuator rod 28, being constrained thereagainst, follows therebehind to allow a closure of valve device 24 to halt the motor of means 80. The V-slot 66 is provided to insure the functioning of this novel device in power tools which rotate unidirectionally, or in power tools which have both forward and reverse drives. The torque responsive clutch assembly 18 will index or slip but one quadrant so as to provide for the camrning of plunger 56 while maintaining a full torque on the workpiece. Therefore, plunger 56 comprises a means for locking up the tool 10 in a fully torqued and halted condition. Both plungers 56 and 54 move forward, to facilitate the travel of rod 28 therebehind and to compress spring 70. Also, one leg of V-slot 66 is caused to move fully across pin 68, and must remain locked thus; plunger 56 is held in this cammed position, the caging plate 38 having completed the one quadrant indexing, and the motor means being at halt. Accord ingly spring 70 is locked in compression and device 24, in response to spring 26, keeps the motor means at halt. Upon withdrawal of the tool 10 from the workpiece, spring 70 re-cams and centers plunger 56 on pin 68; the tool 10 is ready for further use.

The disposition of my novel clutch, as shown in FIG. 2, is one in which the motor means are at halt. Clutch driver 46 is fully forward, under the urging of a compression spring 72 disposed between clutch jaw 44 and clutch driver 46. Both jaw 44 and driver 46, even so, are engaged for concurrent rotation theretogether, but displaced therebetween to facilitate the halting of the motor means. The hexagonal bore portion 50 and circular bore portion 52 of shaft 16 join at line I, as shown in FIG. 2. Thus, plunger 56 is fully within bore portion 52; plunger 54 is fully within bore portion 50. The latter disposition is shown in FIG. 4; the former disposition is shown in FIG. 5. Clearly, then, were there any rotation of shaft 16, this would be ineffective toward rotation of plunger 56. And it is the achievement of this disposition which facilitates the halting of the motor means 80.

Balls 36, at torque limit, index one radial position; thus, the relative, radial movement between plate 38 and clutch jaw 44 is some 60 of arc. The camming displacement thereof rotates plunger 56 a same 60 of arc, after which it is disposed in bore portion 52. The tool being at torque limit, pin 68 rotates not at all. When the tool is removed from the torqued workpiece, clutch driver 46 is free to move axially, forwardly. In doing so, pin 68 carried thereby finds the apex of V-slot 66, and plunger 56 freely positions the apex thereof about pin 68 under the urging of spring 70. The last, beyond-torque turn of shaft 16 will have rotated bore portion 50 some 60 of arc relative to plunger 56. However, plunger 56, in being hexagonal, and being positionally normalized on pin 68, is again linearly aligned for re-engagement with bore portion 50 but now in 60 of relative displacement from the engagement last made.

Bore portion 50 and plunger 56 are hexagonally configured, in this preferred embodiment of my invention. Thus, the 60 of relative displacement is effected. Obviously, though, the mating bore portion 50 and plunger 56 could be of other geometric configurations: octagonal, triangular, square, etc. to yield 45, 120, or of relative displacement, without departing from the teaching of my invention. The angular lay and extent of V-slot 66 are such as to effect the amount of displacement which is requisite for proper functioning of plunger 56 and complementary to the hexagonal geometry here taught. Simply by varying the angular lay and extent, or both, in the formation of V-slot 66 it is possible to realize a complementary interaction of the latter with octagonal, triangular, square or other geometry.

In an alternate embodiment of my inventive clutch camming arrangement, shown in FIG. 6, I find it possible to dispense with the hexagonal bore 50, and the hexagonal configuration of the one plunger. The clutch driver 46' carries the stub shaft 62 to which pin 68' is fixed. A spring 70 is disposed about stub shaft 62, the ends thereof fixed in clutch driver 46 and a round, first plunger 56. Power take-off shaft 16' has but a single circular bore 52 formed therein to receive the stub shaft 62 and first plunger 56, as Well as a round, second plunger 54'. Narrow, and oppositely disposed, axiallyextended slits 60' are formed in shaft 16 to receive a pin 58 which is passed through second plunger 54'. In the manner described earlier, with respect to pin 58 and plunger 54, shown in FIG. 2, of the first embodiment, pin 58 provides for rotation of plunger 54 with shaft 16, and limits the axial travel thereof.

Plungers 54 and 56' have saw-tooth-like ridges 74 formed on the respective, interfacing ends of each, whereby rotation is imparted from plunger 54' to plunger 56' upon engagement of said plungers theretogether. Finally, plunger 56' has angular slots 76 formed therein and therethrough, on opposite sides thereof, to receive pin 68, as shown in FIG. 7.

When the power tool is addressed to a workpiece, clutch driver 46' is translated rearwardly. This causes an engagement of ridges 74 and results in an interfacing coupling of plungers 54' and 56'. Further, plungers 56' and 54 are caused to translate axially, rearwardly also, effecting a movement of actuator rod 28 and the enabling of the motor means 80. The motor means powers the take-off shaft 16 and, through pin 58' causes a clockwise rotation, i.e., from right to left, as viewed in the drawings, of plunger 54 and plunger 56 engaged therewith. Further, drive is imparted through a similar clutch assembly 18 (FIG. 2) to torque clutch driver 46'. When the workpiece being addressed is fully torqued, via the agency of clutch driver 46, the latter will halt, clutch assembly 18 facilitating this effect. Accordingly, pin 68 is halted, while plungers 54 and 56' continue to execute what will be a last, powered turn. Constrained together under the urgings of springs 70 and 26 (FIG. 3), said plungers turn in unison. Yet plunger 56 is also cammed forwardly, slots 76 being caused to track along pin 68, compressing spring 70. Plunger 54' yields to spring 26 and follows therealong, and valve 24 (FIG. 3) closes to halt the motor means 80.

In counter-clockwise rotation, the motor means is not brought to a halt when the workpiece is fully torqued but, as study of the ridges 74 will evidence, the continuing rotation of plunger 54' will not be imparted to plunger 56'. Ridges 74 on plunger 56' will remain stationary, and ridges 74 on plunger 54' will continuously index thereabout, until the power tool is withdrawn from the workpiece. Thus, this alternate embodiment of my novelty cammed clutch can be used in a uni-directionally-driven power tool, and is responsive to torque to halt the motor, and in a bi-directionally-driven power tool, my latter embodiment being responsive to torque to halt the motor in one direction. In both applications my latter embodiment, no less than the former, preferred embodiment, achieves and maintains full torque on the workpiece when addressed for clockwise or counterclockwise rotation.

I claim:

1. A clutch, for use with a power tool having a chuck, and a power train, including motor means and a gear train, for rotation of said chuck, comprising:

first means disposed between said chuck and said power train for translating motion therebetween and, responsive to a given torque loading of said chuck, for prohibiting said translation therebetween;

said first means including second means carried thereby for enabling and halting the rotation of said motor means;

said second means being disposed for a first motion relative said gear train for enabling said motor means, and disposed for at least a second motion transverse to said first motion, with the achievement of said given torque, for halting said motor means; and

a turn-on and turn-off device coupled to said second means for co-operation therewith for enabling and halting said motor means; and wherein said second means comprise a plurality of plungers, and

a rod disposed between said plurality and said device; said plurality being movable to translate said rod to cause the latter to actuate said device.

2. The invention, according to claim 1, further including:

first biasing means engaging said plurality to urge the latter against said rod so as to tend to actuate said device in a turn-on mode of operation; and

second biasing means disposed to urge said rod away from said device so as to tend to actuate said device in a turn-off mode of operation.

3. The invention, according to claim 1, wherein:

said plurality includes first and second plungers; and

further including means coupling one of said first and second plungers with said chuck to provide for axial and rotary relative motion therebetween.

4. The invention, according to claim 1, wherein:

second means include camming means to provide for axial and rotary relative motion between said chuck and said plurality to cause the latter to overcome the urging of said first biasing means.

5. The invention, according to claim 1, wherein:

said second means include camming means to provide for axial and rotary relative motion between said chuck and said plurality to facilitate response of said plurality to the urging of said first biasing means.

6. The invention, according to claim 5, wherein:

said camming means comprise a camming surface,

which is presented by a given plunger of said plurality, and a cam follower, fixed to said chuck, disposed to track along said camming surface.

7. The invention, according to claim 6, wherein:

said chuck and said plurality are co-axially disposed, said camming surface comprises angular slotting formed in said given plunger, and said cam follower comprises a pin in penetration. of said given plunger via said angular slotting.

8. The invention, according to claim 1, further comprising:

a power takeoff shaft coupled between said power train and said chuck to provide for rotation of the latter, said shaft having an axial bore formed in the center thereof; and

wherein said plurality is disposed within said axial bore.

9. The invention, according to claim 8, wherein:

said axial bore has a polygonal configuration along a section thereof; and

one plunger of said plurality is of polygonal shape and of a dimension to facilitate disposition thereof in said section for axial movement therewithin and for cooperative rotary motion therewith.

10. The invention, according to claim 1, wherein:

said chuck has a round stub shaft extending therefrom and one plunger of said plurality has a circular bore formed therein which receives said stub shaft to allow said one plunger and said chuck to effect relative axial and rotary movement therebetween.

11. The invention, according to claim 1, further comprising:

means coupling said power train with one plunger of said plurality to effect rotation of the latter. 12. The invention, according to claim 1, further comprising:

means coupling said power train with one plunger of said plurality to effect rotation of the latter; and wherein said plungers of said plurality have means integral therewith for causing at least one plunger of said plurality to engage another plunger of said plurality to effect rotation of the latter by the former.

13. The invention, according to claim 1, further comprising:

means coupling said power train with one plunger of said plurality to effect rotation of said one plunger; and

wherein said plungers of said plurality have means integral therewith for causing at least one plunger of said plurality to engage another plunger of said plurality to effect rotation of the latter by the former upon rotation of the former in a given direction and for causing disengagement of said one plunger and said another plunger upon rotation of said one plunger in a direction which is the reverse of said given direction.

14. The invention, according to claim 1, wherein:

said second means are disposed for a first motion relative said gear train, a second motion transverse to said first motion, and a third motion transverse to both said first and second motions.

15. A power-operated tool comprising:

a rotary motor;

supply means for conducting motor-driving energy to said motor;

control means having alternate positions and controlling said supply means so that in one position it prevents said energy from being supplied to said motor, and in its other position, it allows said energy to flow to said motor, said control means being normally in said one position and including biasing means urging said control means to said one position;

a tool spindle adapted to be connected to a workpiece for applying a torque load to the workpiece and operative, when pressed against the workpiece, to move said control means to its other position;

a torque responsive clutch which is normally engaged to interconnect said spindle to said motor, said clutch being operative, in response to a predetermined torque load on said spindle, to disengage wherein said motor can rotate relative to said spindle;

spring means operative, in its normal position, when said clutch is engaged and said spindle is pressed against a workpiece, to urge and hold said control means in its other position, said clutch being operative, when moving to its disengaged position, to move said spring means to an inoperative position wherein said spring means no longer holds said control means in its other position; and

lock means movable in response to the disengaging of said clutch to hold said spring means in said inoperative position wherein said control means can return to said one position preventing said motordriving energy from flowing to said motor.

16. The tool of claim 15, wherein:

said lock means is operative, in response to the withdrawing fo the spindle from the workpiece, to unlock said spring means and allow it to return to its normal position.

17. A fluid-operated rotary tool comprising:

a housing including a fluid-operated rotary motor;

a supply passage for conducting power fluid to said motor;

a throttle valve in said passage movable between alternate positions closing and opening said passage,

said throttle valve being normally closed and including biasing means urging said throttle valve to a closed position;

a tool spindle adapted to be connected to a workpiece for applying a torque load to the workpiece and operative, when pressed against the workpiece, to move said throttle valve to its open position;

a torque responsive clutch interconnecting said spindle to said motor, said clutch being operative, in response to a predetermined torque load on said spindle, to disengage and disconnect said spindle from said motor;

spring means operative in its normal position, when said clutch is engaged and said spindle is pressed against the workpiece, to hold said throttle valve open during the operation of the tool, said clutch being operative, when moving to a disengaged position, to move said spring means to an inoperative position wherein said spring means no longer holds said throttle valve open; and

lock means cooperating with said clutch and movable to a position in response to the disengaging of said clutch wherein it locks and holds said spring means in said inoperative position wherein said biasing means moves said throttle valve to its closed position wherein the valve prevents the power fluid from driving said motor.

18. The tool of claim 17, wherein:

said lock means is operative, in response to the withdrawal of said spindle from the workpiece, to unlock said spring means and allow it to return to its normal position.

19. A fluid-operated rotary tool comprising:

a housing including a fluid-operated rotary motor;

a supply passage for conducting power fluid to said motor;

a throttle valve in said passage movable between alternate positions closing and opening said passage, said throttle valve being operable by an operator to an open position to start said motor and including biasing means urging said throttle valve to closed position;

a tool spindle adapted to be connected to a workpiece for applying a torque load to the workpiece;

a torque responsive clutch interconnecting said rotary drive from said motor to said spindle, said clutch being operative, in response to a predetermined torque load on said spindle, to progressively release and interrupt said rotary drive to said spindle; and

control means operative in response to the releasing of said clutch, to progressively close said throttle valve in step with the releasing of said clutch whereby said motor is progressively stopped as said clutch progressively releases.

20. The tool of claim 19, wherein:

said control means includes spring means which normally holds said throttle valve in its open position after being moved to the open position by an operator.

References Cited UNITED STATES PATENTS 3,220,526 11/1965 Gattiker 192150 3,235,050 2/1966 Schoppe et al. 192150 3,288,258 1l/l966 Taylor l92150 3,289,715 12/1966 De Grofi et al. 192150 XR 3,298,481 l/1967 Schaedler et al. 192-l50 3,322,205 5/1967 Amtsberg et al. 192-150 XR CARLTON R. CROYLE, Primary Examiner A. O. HERRMANN, Assistant Examiner US. Cl. X.R. 

